An Observational Dosimetric Study in Definitively Treated Primary Head and Neck Cancers: To Assess the Effect of Weight Loss and Change in Lateral Neck Dimensions on the Difference Between Dose Planned and Received by the Parotid(s) and Correlation with Adaptive Radiation Therapy.

Purpose: The head and neck cancer (HNC) literature is rife with reports of differences in planned versus actual radiation doses to the parotid gland (PG) due to changes in anatomy during the course of radiation therapy. We prospectively studied and quantified changes in planned and delivered doses due to weight loss and changes in lateral neck dimensions. Methods and Materials: Sixty patients were enrolled in this prospective non-randomized observational study. The inclusion criterion was having a newly diagnosed, histologically proven squamous cell carcinoma of HNC. Weight loss (WL) and change in lateral neck dimensions (LND) were assessed weekly, and new hybrid plans were generated using interval replanning CT scans. Dose variations were monitored and extrapolated for replanning CT scans and correlated with WL and change in LND. Results: The Pearson correlation coefficients for WL and difference in Dmean of ipsilateral and contralateral PG was 0.3292 (P = .0124) and 0.4232 (P = .0010), respectively. There was significantly higher change in the Dmean of bilateral PG (Ipsilateral(I) > contralateral(C)) in patients who experienced WL of >5%. Change in LND correlated with difference in Dmean of ipsilateral PG at 0.4829 (P = .0001) and difference in D50 at 0.4146 (P < .0013). Contralateral PG correlated with difference in Dmean at 0.5952 (P < .0001). The difference in Dmean for ipsilateral PG was 1.8535 Gy for those showing reduction in LND of >1 cm compared with 0.8596 Gy (P = .0091) for those who had ≤1 cm reduction in LND. Conclusions: Either WL of >5% or reduction in LND of >1 cm can be used as an external parameter to help select patients who might benefit most from replanning and adaptive radiation therapy.

Dosimetric comparison of O-ring versus conventional C-arm linear accelerator for volumetric modulated arc therapy (VMAT) of head and neck cancer and carcinoma cervix patients.

The objective of this study is dosimetric comparison between the O-ring Halcyon and C-arm Clinac iX linac for volumetric modulated arc therapy (VMAT) plans for head & neck (H&N) cancer and carcinoma cervix patients. Total 60 patients of H&N cancer and carcinoma cervix were enrolled prospectively from March 2021 to March 2023. VMAT plans with 6 MV photons for Halcyon and Clinac iX were generated and compared for each patient by dose volume histogram for planning target volume coverage and organ at risk (OAR) sparing. There were no differences in between both the linacs for PTV D2% and D98%, homogeneity index, conformity index, Dmax (maximum dose) and Dmean (mean dose) of OAR. Halcyon had significantly shorter treatment time compared to Clinac iX. Halcyon delivered higher integral dose and monitor units. O-ring Halcyon produces VMAT plans comparable to other C-arm linacs for H&N and carcinoma cervix patients.

A prospective study to assess and quantify the setup errors with cone-beam computed tomography in head-and-neck cancer image-guided radiotherapy treatment.

Introduction: This study was done to quantify the translational setup errors with cone-beam computed tomography (CBCT) in the image-guided radiation therapy (IGRT) treatment of head-and-neck cancer (HNC) patients. Aims: The objective was to quantify the setup errors by CBCT. Methodology: One hundred patients of HNC were enrolled from March 2020 to March 2021 for IGRT treatment. Pretreatment kV-CBCT images were obtained at the first 3 days of irradiations, and setup error corrections were done in the mediolateral (ML), superior-inferior (SI), and anterior-posterior (AP) directions. Subsequently, a weekly kV-CBCT was repeated for whole duration of radiotherapy for the next 6-7 weeks. Adequacy of planning target volume (PTV) margins was assessed by van Herk's formula. Results: Total 630 CBCT scans of 100 patients were analyzed. Setup errors greater than 3 mm and 5 mm were seen in 11.4% and 0.31% of the patients, respectively. Systematic errors and random errors before correction in ML, SI, and AP directions were 0.10 cm, 0.11 cm, and 0.12 cm and 0.24 cm, 0.20 cm, and 0.21 cm, respectively. Systematic errors and random errors after correction in ML, SI, and AP directions were 0.06 cm, 0.07 cm, and 0.07 cm and 0.13 cm, 0.10 cm, and 0.12 cm, respectively. Conclusion: CBCT at the first 3 fractions and then weekly during radiotherapy is effective to detect the setup errors. An isotropic PTV margin of 5 mm over clinical target volume is safe to account for setup errors, however, in the case of close organ at risk, or with IGRT, a PTV margin of 3 mm can be considered.

A randomized prospective study comparing acute toxicity, compliance and objective response rate between simultaneous integrated boost and sequential intensity-modulated radiotherapy for locally advanced head and neck cancer.

PURPOSE: Intensity-modulated radiotherapy (IMRT) provides higher dose to target volumes and limits the dose to normal tissues. IMRT may be applied using either simultaneous integrated boost (SIB-IMRT) or sequential boost (SEQ-IMRT) technique. The objectives of this study were to compare acute toxicity and objective response rates between SIB-IMRT and SEQ-IMRT in patients with locally advanced head and neck cancer. MATERIALS AND METHODS: Total 110 patients with locally advanced carcinoma of oropharynx, hypopharynx, and larynx were randomized equally into the two arms (SIB-IMRT vs. SEQ-IMRT). Patients in SIB-IMRT arm received dose of 66 Gy in 30 fractions, 5 days a week, over 6 weeks. SEQ-IMRT arm's patients received 70 Gy in 35 fractions over 7 weeks. Weekly concurrent cisplatin chemotherapy was given in both arms. Patients were assessed for acute toxicities during the treatment and for objective response at 3 months after the radiotherapy. RESULTS: Grade 3 dysphagia was significantly more with SIB-IMRT compared to SEQ-IMRT (72% vs. 41.2%; p = 0.006) but other toxicities including mucositis, dermatitis, xerostomia, weight-loss, incidence of nasogastric tube intubation and hospitalization for supportive management were similar in both the arms. Patients in SIB-IMRT arm showed better treatment-compliance and had significantly less treatment-interruption compared to SEQ-IMRT arm (p = 0.028). Objective response rates were similar in both the arms (p = 0.783). CONCLUSION: Concurrent chemoradiation with SIB-IMRT for locally advanced head and neck cancer is well-tolerated and results in better treatment-compliance, similar objective response rates, comparable incidence of mucositis and higher incidence of grade 3 dysphagia compared to SEQ-IMRT.

A prospective, comparative analysis of acute toxicity profile between three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) in locally advanced head and neck cancer patients.

INTRODUCTION: The advances of modern radiotherapy have emerged with the development of conformal radiotherapy techniques, such as the three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT). We prospectively compared acute toxicities and treatment-compliance between IMRT and 3DCRT in patients with locally advanced head and neck carcinoma. METHOD: 80 patients were enrolled in this comparative prospective non-randomized study. Inclusion criteria were patients with locally advanced carcinoma of hypopharynx, oropharynx and larynx. 40 patients were treated with IMRT and 40 patients with 3DCRT to dose of 70 Gy in 35 fractions, along with concurrent cisplatin weekly chemotherapy. All patients were assessed weekly during chemoradiotherapy treatment and after 3 months of the treatment. RESULTS: 15 patients (38.4%) versus 8 patients (20.51%) developed grade 3 mucositis in the 3DCRT and IMRT group respectively (p= <0.001). At three months post chemo-radiotherapy treatment, 17 patients (43.6%) versus 7 patients (17.9%) had grade 2 dysphagia in 3DCRT and IMRT group respectively (p = 0.029). At three months post radiotherapy, grade 3 xerostomia was seen in 3 patients (7.6%) in 3DCRT group versus no patient (0%) in IMRT group (p = 0.006). IMRT group had lower incidence of grade 3 dermatitis (p = 0.043), weight loss of the patients during the treatment (p = 0.126), lesser requirement of nasogastric intubation (p = 0.003) and better treatment-compliance (p = 0.336) compared to 3DCRT. CONCLUSION: IMRT reduced the incidence of severe mucositis, dysphagia, xerostomia, weight-loss of the patients, requirements for nasogastric tube and it improved the treatment-compliance compared to 3DCRT in locally advanced head neck cancer patients treated by chemo-radiotherapy.

Plasmacytoma of the Skull-base: A Rare Tumor.

Plasmacytoma of the skull-base is a rare entity. Differential diagnosis includes chordoma, osteosarcoma, carcinoma nasopharynx, meningioma, metastatic carcinoma, lymphoma, and multiple myeloma. Accurate and precise diagnosis is extremely important for plasmacytoma of the skull-base as its treatment and prognosis is different from other skull-base lesions. A 41-year-old man presented with concerns of headache, diplopia, and left eye strabismus. A magnetic resonance image (MRI) of his brain showed a large expansile mass measuring 51 mm involving the clivus and central skull-base. Trans-sphenoidal tumor decompression was done. A biopsy confirmed the plasmacytoma. A positron emission tomography-computed tomography (PET-CT) scan showed a single 2-(18F) fluoro-D-glucose (FDG) avid lesion at the skull-base. The results of all other relevant investigations such as hemoglobin, renal function test, serum calcium, serum protein immunoelectrophoresis, serum quantitative immunoglobulin, bone marrow biopsy, serum lactate dehydrogenase, and beta-2 microglobulin levels were within normal limits. He was treated with radical radiotherapy. He developed complete clinical response after radiotherapy.